System, method and apparatus for wireless synchronizing three-dimensional eyewear

ABSTRACT

An application for transmission of a three-dimensional eyewear synchronization signal to synchronize the operation of shutters of three-dimensional eyewear uses an industry standard wireless transmission technique. To compensate for inherent latencies of such transmission techniques, the latencies are measured and monitored to determine expected latencies and the shutter synchronization signal is skewed by the latency. In some embodiments, the synchronization signal is further adjusted by a user skew control.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to U.S. patent application titled “PIXELSYSTEM, METHOD AND APPARATUS FOR SYNCHRONIZING THREE-DIMENSIONALEYEWEAR,” filed Feb. 1, 2010, attorney docket 10_(—)0001. Thisapplication is also related to U.S. patent application titled “FRAMESYSTEM, METHOD AND APPARATUS FOR SYNCHRONIZING THREE-DIMENSIONALEYEWEAR,” filed Feb. 1, 2010, attorney docket 10_(—)0002. Thisapplication is also related to U.S. patent application titled “PIXELBASED THREE-DIMENSIONAL ENCODING METHOD,” filed Feb. 1, 2010, attorneydocket 10_(—)0003. This application is also related to U.S. patentapplication titled “FRAME BASED THREE-DIMENSIONAL ENCODING METHOD,”filed Feb. 1, 2010, attorney docket 10_(—)0004.

FIELD

This invention relates to the field of display devices worn over anindividual's eyes and more particularly to a system for synchronizingthe display devices with content presented on a display screen.

BACKGROUND

There are several ways to present a three-dimensional image to a viewerof a television. The common aspect of the existing methods is to presentan image or frame from two perspectives, a left-eye perspective of thecontent to the left eye and present an image or frame from a right-eyeperspective to the right eye. This creates the proper parallax so thatthe viewer sees both perspectives and interprets what they are seeing asthree-dimensional.

Early three-dimensional content was captured using two separate camerasaimed at the subject but slightly separate from each other providing twodifferent perspectives. This simulates what the left eye and right eyesee. The cameras simultaneously exposed two films. Usingthree-dimensional eyewear, the viewer looks through one film with theleft eye and the other film with the right eye, thereby seeing whatlooks like a three-dimensional image.

Progressing to motion pictures, three-dimensional movies were producedin a similar way with two cameras, but the resulting images were colorencoded into the final film. To watch the film in three-dimension,eyewear with colored filters in either eye separate the appropriateimages by canceling out the filter color. This process is capable ofpresenting a three-dimensional movie simultaneously to a large audience,but has marginal quality and, because several colors are filtered fromthe content, results in poor color quality, similar to a black and whitemovie.

More recently, personal eyewear have been made that have two separateminiature displays, one for each eye. In such, left content is presentedon the display viewed by the left eye and right content is presented onthe display viewed by the right eye. Such systems work well, but requirea complete display system for each viewer.

Similar to this, Eclipse methods uses a common display, such as atelevision, along with personal eyewear that have fast-response shuttersover each eye. In such, the left eye shutter is open allowing light topass, the right eye shutter is closed blocking light and the televisiondisplays left-eye content, therefore permitting the light (image) fromthe television to reach the left eye. This is alternated with closing ofthe left eye shutter, opening of the right eye shutter and displayingright-eye content the television. By alternating faster than the typicalhuman response time, the display appears continuous and flicker-free.

One problem with the latter two methods is that the three-dimensionalcontent must be encoded on, for example, a disk and decoded by a playerthat switches between left/right eye content in synchronization with theleft-eye and right-eye shutter. With such, one cannot connect anindustry standard player (e.g. BlueRay or DVD) to an industry standardtelevision (e.g., Plasma or LCD television) and watch three-dimensionalcontent with a set of three-dimensional eyewear. Another problem is insynchronizing the eyewear with the images displayed on the television.Currently, the three-dimensional eyewear needs to be connected to thetelevision by a low-latency connection, usually a wired connection toassure the proper eyewear shutter is open when the corresponding imageis displayed (the image that relates to the eye associated with the openshutter). Although wireless transmission techniques such as WiFi andBluetooth are well-known, low-cost and readily available, latency is ofconcern for transmitting a synchronization signal. For example, if att0, the television displays a left-eye frame and at the same timetransmits a Bluetooth packet to eyewear, the eyewear doesn't know thepacket has arrived until t0+l, where l is the latency of thetransmission. The latency, in an ideal transmission, is equal to thepacket size divided by the transmission speed. For high-speedtransmission such as 54 Mbs 802.11, the latency is normally rather low,but the latency is often increased due to other wireless devicesutilizing the same bandwidth, transmission errors, noise andinterference (e.g. interference from a microwave oven, etc). Therefore,the latency ranges from microseconds to many milliseconds. In such atransmission system, when synchronization is skewed due to unpredictablelatency, the wrong eye shutter is open for too long, allowing each eyeto partially see content/frames designated for the other eye; causingblurring or other artifacts that detract from the three-dimensionalviewing experience.

What is needed is a three-dimensional presentation system that utilizesexisting packet wireless transmission techniques.

SUMMARY

In order to synchronize the operation of shutters of three-dimensionaleyewear, an industry standard wireless transmission technique isutilized. To compensate for inherent latencies of such techniques, thelatencies are measured and monitored to determine expected latencies andthe shutter synchronization signal is skewed by the measured latency. Insome embodiments, the synchronization signal is further adjusted by auser skew control.

The eyewear includes shutters over each eye that open and close fastenough to keep up with the frame rate of the television. A wirelesssignal is periodically sent from the television or other base-locateddevice to the eyewear. The eyewear receives the wireless signal anddetermines a latency between the start of the transmission and theactual start and/or end of reception and subtracts the latency from eachsuccessive reception of the wireless signal to operate the shutters insynchronization with the television/base-located device. Examples of thewireless transmission technique include, but are not limited to, WiFi(802.11x) and Bluetooth.

A content delivery mechanism (e.g. Internet, cable, fiber-optic, DVD,BlueRay) delivers the content to a television. A circuit associated withthe television or external to the television determines when either aleft-eye frame or a right-eye frame is being displayed and transmits aminimal amount of information to the eyewear by a wireless transmission(e.g. WiFi or Bluetooth). The wireless packet is received by thethree-dimensional eyewear where it is used to properly shutter the firsteye and the second eye. A latency value is subtracted from (or added to)the time of reception, resulting in a synchronization point (e.g., apoint in time when the left-eye content frame is displayed and left eyeshutter should be open). After reception of a sequence of packets, theeyewear determines the expected timing of multiple synchronizationpoints, thereby generating an internal synchronization signal that isclosely synchronized with the changing of frames displayed on thetelevision, left content frame to right content frame and right contentframe to left content frame. In some systems, a phased-locked loop isused to continue operation of the shutters during periods when thelatency is significantly longer than expected; the transmission of thesynchronization signal is blocked; or otherwise the transmission of thesynchronization signal interrupted. In some systems, the skew isadjustable up or down to provide a fine adjustment of thesynchronization should the latency calculation be less than optimal.

In one embodiment, a three-dimensional eyewear synchronization system isdisclosed. The three-dimensional eyewear synchronization system has atransmitter that sends a synchronization packet indicatingsynchronization timing between left-eye content and right-eye contentbeing displayed. The three-dimensional eyewear has a receiver and ashutter system for alternating image viewing to each eye of a wearer.The three-dimensional eyewear receives the synchronization packet,determines the transmission latency and uses a time of receipt of thesynchronization packet and the latency to generate an eyewear internalsynchronization timing that approximates the synchronization timing. Thethree-dimensional eyewear controls the shutter system responsive to theeyewear internal synchronization timing.

In another embodiment, a method of synchronizing three-dimensionaleyewear to a display of content is disclosed including, at asynchronization point, sending a synchronization packet to thethree-dimensional eyewear then determining a latency of the sending andgenerating an internal synchronization timing in the eyewear bycombining a time of reception of the synchronization packet with thelatency to control eye shutters of the three-dimensional eyewear insynchronization with the internal synchronization timing.

In another embodiment, a three-dimensional eyewear synchronizationsystem is disclosed including a television that has a display and thedisplay presenting left-eye frames and right-eye frames. A deviceassociated with the television is for transmitting a synchronizationpacket is synchronized to which of the left-eye frame and the right-eyeframe is being displayed on the display. Another device associated withthree-dimensional eyewear is for receiving the synchronization packet.There is another device for determining a latency of the transmitting ofthe synchronization packet and another device for synchronizing shuttersof the three-dimensional eyewear using a time of reception of thesynchronization packet and the latency to approximate the timing of thedisplay of the left-eye frames and the right-eye frames.

In another embodiment, a three-dimensional eyewear synchronizationsystem is disclosed including a television, the television having adisplay, the display presenting left-eye frames and right-eye frames anda synchronization signal representing a change between displaying of theleft-eye frame and displaying of the right-eye frame on the display. Thetelevision includes a device for determining a latency of a transmissionof a synchronization packet and a device for transmitting asynchronization packet synchronized to the synchronization signal butretarded in time by the latency (e.g. sent before the synchronizationsignal). The three-dimensional eyewear have a device for receiving thesynchronization packet and have a device for synchronizing shutters tothe reception of the synchronization packet, thereby synchronizingapproximately with the timing of the display of the left-eye frames andthe right-eye frames.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be best understood by those having ordinary skill inthe art by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a plan view of a television and three-dimensionaleyewear of the prior art.

FIG. 2 illustrates a plan view of a television and three-dimensionaleyewear.

FIG. 3 illustrates a schematic diagram of a typical receiver circuit ofthe three-dimensional eyewear.

FIG. 4 illustrates a schematic diagram of a typical receiver circuit ofthe three-dimensional eyewear with adjustable skew.

FIG. 5 illustrates a synchronization timing chart.

FIG. 6 illustrates a block diagram of a typical television system withwireless synchronization transmission.

DETAILED DESCRIPTION

Reference will now be made in detail to the presently preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Throughout the following detailed description,the same reference numerals refer to the same elements in all figures.Throughout the description, the term transmitter and receiver are eitherindependent transmitters or receivers and/or are the transmittersection/receiver section of a transceiver.

Referring to FIG. 1, a plan view of a television 1 and three-dimensionaleyewear 10 of the prior art is described. In prior technology,three-dimensional eyewear 10 functioned with content delivery hardware,such a personal computer or specially equipped television 1. Thepersonal computer or television 1 displays three-dimensional content ona display 2 and controls the eyewear 10 through a cable 18 that providedcontrol of each eye shutter 14/16, synchronizing the eye shutters 14/16to the content being displayed on the display 2. The eyewear oftenincludes frames with ear rests 12. In such systems, content containsleft-eye and right-eye encoded frames. Specialized hardware and/orsoftware in the personal computer or television 1 displays the contentand synchronizes operation of the left/right shutter 14/16 with thedisplay of the content using synchronization signals sent over the cable18.

The cable interface 18 was needed to assure proper timing of the leftshutter 14 and right shutter 16 when left frames and right frames aredisplayed on the display 2. The cables of the prior art create acomfort, distance and safety issue and are not desired.

Referring to FIG. 2, a plan view of a display device (e.g. television) 5and three-dimensional eyewear 50A is described. In this, a transmitterdevice has an antenna 20 integrated in the television 5. As will bedescribed, the transmitter periodically transmits a synchronizationpacket 57 to the three-dimensional eye wear 50A over a wirelesstransmission channel, for example, using WiFi or Bluetooth. In oneexample, the synchronization packet 57 is transmitted each time aleft-eye content frame is displayed on the display 7. Thesynchronization packet 57 is received by an antenna 58 and decodedwithin the eyewear 50A or by an attached circuit to the eyewear 50A (notshown), to control the eyewear shutters 54/56 as will be described.Note, in some embodiments, the eyewear 50A includes ear rests 52 forsupport.

Referring to FIG. 3, a schematic diagram of a typical receiver circuit80 of the three-dimensional eyewear 50A is described. In such, the radiofrequency signal (packet) 57 is received on the antenna 58 anddetected/demodulated by a transceiver 53. The transceiver 53 is anyknown transceiver such as a Bluetooth transceiver or WiFi transceiver.In most packet-based transmission techniques, the entire packet isreceived and error checked/corrected, then an acknowledgement istransmitted back to the sender (e.g. television 5). The transceiver 53emits a synchronization signal 70 when it receives a timing packet 57.The synchronization signal 70 is connected to a timing circuit 55. It isanticipated that in some embodiments, the same transceiver 53 alsoreceives other packets for use within the eyewear 50A for other purposessuch as audio packets, etc.

The transceiver 53 determines or receives a latency time, l, and relatesthe latency time, l, to the timing circuit 55 by a latency interface 72which is any interface as known in the industry such as a voltage,current, digital value (e.g. I²C), etc. In some embodiments, the latencytime, l, is determined by the transceiver 53 based on the packet 57 sizeand the current transmission rate. The transceiver knows thetransmission rate, which often varies up and down based upon collisions,interference, competing wireless networks, etc. In other embodiments,the latency, l, is determined at the television 5 (or other base-device)by measuring the time from start of transmission of the packet 57 untilstart or end of reception of the acknowledgement, then allocating partor all of the time to the latency l. For example, if the transmissionpacket length is 128 bits and the acknowledgement packet length is 64bits, and the time measured is 12 microseconds, then ⅔ of the time or 8microseconds is allocated to the latency l. In such, the latency valueis then transmitted as part of the next packet 57, received by thetransceiver 53 and provided to the timing circuit 55 over the latencyinterface 72 for determining synchronization of the shutters 54/56.

The timing circuit locks onto the synchronization signal 70 and adds orsubtracts the latency value to generate a left-eye (Q) control signaland a right-eye (−Q) that are coupled to the left-eye shutter 54 andright-eye shutter 56, respectively, by shutter drivers 60/59. In thepreferred embodiment, the timing circuit 55 includes aphased-locked-loop that provides the left-eye and right-eye controlsignals during a loss of the synchronization signal 70, for example wheninterference temporarily disables transmission of the packets 57. Insome embodiments, the phase-locked-loop also performs a filter function,ignoring spurious extreme latency values that occur, for instance, whenthe wireless interface is used to transfer data, etc.

Referring to FIG. 4, a schematic diagram of a typical receiver circuit81 of the three-dimensional eyewear 50A with adjustable skew isdescribed. In such, the radio frequency signal (packet) 57 is receivedon the antenna 58 and detected/demodulated by a transceiver 53. Thetransceiver 53 is any known transceiver such as a Bluetooth transceiver,WiFi transceiver or infrared transceiver. In most packet-basedtransmission techniques, the entire packet is received and errorchecked/corrected, then an acknowledgement is transmitted back to thesender (e.g. television 5). The transceiver 53 emits a synchronizationsignal 70 when it receives a timing packet 57. The synchronizationsignal 70 is connected to a timing circuit 55. It is anticipated that insome embodiments, the same transceiver 53 also receives other packetsfor use within the eyewear 50A for other purposes such as audio packets,etc.

The transceiver 53 determines or receives a latency time, l, and relatesthe latency time, l, to the timing circuit 55 by a latency interface 72which is any interface as known in the industry such as a voltage,current, digital value (e.g. I²C), etc. In some embodiments, the latencytime, l, is determined by the transceiver 53 based on the packet 57 sizeand the current transmission rate. The transceiver knows thetransmission rate, which often varies up and down based upon collisions,interference, competing wireless networks, etc. In other embodiments,the latency, l, is determined at the television 5 (or other base-device)by measuring the time from start of transmission of the packet 57 untilstart or end of reception of the acknowledgement, then allocating partor all of the time to the latency l. For example, if the transmissionpacket length is 128 bits and the acknowledgement packet length is 64bits, and the time measured is 12 microseconds, then ⅔ of the time or 8microseconds is allocated to the latency l. In such, the latency valueis then transmitted as part of the next packet 57, received by thetransceiver 53 and provided to the timing circuit 55 over the latencyinterface 72 for determining synchronization of the shutters 54/56.

The timing circuit locks onto the synchronization signal 70 and adds orsubtracts the latency value l to generate a left-eye (Q) control signaland a right-eye (−Q) that are coupled to the left-eye shutter 54 andright-eye shutter 56, respectively, by shutter drivers 60/59. In thepreferred embodiment, the timing circuit 55 includes aphased-locked-loop that provides the left-eye and right-eye controlsignals during a loss of the synchronization signal 70, for example wheninterference temporarily disables transmission of the packets 57. Insome embodiments, the phase-locked-loop also performs a filter function,ignoring spurious extreme latency values that occur, for instance, whenthe wireless interface is used to transfer data, etc.

In this example, since the latency value is a prediction and hasinherent, minor inaccuracies due to interference, distances,reflections, etc, a skew control is provided. Any known skew controldevice is anticipated such as up/down buttons 61/63 (as shown), thumbwheels, rotary controls such as potentiometers, etc. In the exampleshown, the skew control includes an up-skew 61 and a down-skew 63 whichmoves the synchronization timing forward or backward, respectively. Insuch, the user adjusts the skew for maximum viewing enjoyment.

Referring to FIG. 5, an exemplary synchronization timing chart isdescribed. In this example, the alternation of the eye shutters 54/56 isintended to occur during the leading edge transition and falling edgetransition of the synchronization signal 90 at the television 5. It isanticipated that when non-three-dimensional content is displayed, aspecial transmission packet is sent to signal the eyewear 50A to openboth shutters 54/56.

In one embodiment, the internal television 5 (or other base-device) hasan internal synchronization signal 90 that is true (1-value, positive,etc) when left-eye content is displayed on the display 7 and is false(0-value, zero, etc) when right-eye content is displayed on the display7. Ideally, the left-eye 54 shutter opens when the internalsynchronization signal 90 is true and closes when the internalsynchronization signal 90 is false and the right-eye shutter 56 is openswhen the internal synchronization signal 90 is false and closes when theinternal synchronization signal 90 is true. The television 5 (or otherbase-device) begins transmission of a synchronization packet 57 at t₀and the transceiver 53 does not have a completely received and processedpacket 57 until t₀+l. At t₀+l, the transceiver 53 transitions the outputsynchronization signal 70 from zero to one to signal the timing circuit55. This synchronization signal 70 lags the television's 5 internalsynchronization signal 90 and is not directly used to control shutteringof the left-eye shutter 54 and right-eye shutter 56 because suchshuttering would result in blurred images and/or other undesirableartifacts. The eyewear synchronization signal 70 is combined with thelatency value l to recreate an eyewear internal synchronization signal96 that closely aligns with the television 5 internal synchronizationsignal 90. In this example, the latency value l is determined during thefirst synchronization packet 57 transmission at t0 and is subsequentlysubtracted from the eyewear synchronization signal 70 to determine thepositive transition for the internal synchronization signal 98. Afterreceiving two synchronization packets at t0 and t2, the timing circuit55 determines the full cycle time by subtracting t₀+l from t₁+l. Thetiming circuit 55 divides the full cycle time by two to determine thehalf-cycle time (e.g. the time each shutter 54/56 alternate). The timingcircuit determines when the leading edge 97 of the internalsynchronization signal 96 will occur by subtracting the latency value lfrom the internal synchronization signal 94 pulse at t₂ and adding onefull cycle time. The timing circuit determines when the falling edge 98of the internal synchronization signal 96 will occur by adding the halfcycle time to the time of the leading edge 97. This sequence continuesuntil any loss of the synchronization packets 57, at which time, it ispreferred, but not required, that the timing circuit include a phaselocked loop that locks onto the internal synchronization signal 96 andcontinues the operation of the shutters 54/56 until the synchronizationpackets 57 are again received.

The third waveform 94 represents the transmission of an acknowledgementpacket from the eyewear 50A to the television 5. In general, mostwireless protocols use acknowledgement packets to signal the transmitterof successful reception of packets such as the synchronization packet57.

Referring to FIG. 6, a first exemplary schematic view of an exemplarytelevision will be described. This figure is intended as arepresentative schematic of a typical monitor/television 5 and inpractice, some elements are not present in some monitors/televisions 5and/or additional elements are present in some monitors/televisions 5 asknown in the industry. In this example, a display panel 7 is connectedto a processing element 100. The display panel 7 is representative ofany known display panel including, but not limited to, LCD displaypanels, Plasma display panels, OLED display panels, LED display panelsand cathode ray tubes (CRTs).

The processing element 100 accepts video inputs and audio inputsselectively from a variety of sources including an internal televisionbroadcast receiver 102, High Definition Multimedia Interface (HDMI), USBports and an analog-to-digital converter 104. The analog-to-digitalconverter 104 accepts analog inputs from legacy video sources such asS-Video and Composite video and converts the analog video signal into adigital video signal before passing it to the processing element. Theprocessing element controls the display of the video on the displaypanel 7.

Audio emanates from either the broadcast receiver 102, the legacy source(e.g., S-Video) or a discrete analog audio input (Audio-IN). If theaudio source is digital, the processing element 100 routes the audio toa digital-to-analog converter 106 and then to an input of a multiplexer108. The multiplexer 108, under control of the processing element 100,selects one of the audio sources and routes the selected audio to theaudio output and an internal audio amplifier 110. The internal audioamplifier 110 amplifies the audio and delivers it to internal speakers134/136.

The processing element 100 accepts commands from a remote control 111through remote receiver 113. Although IR is often used to communicatecommands from the remote control 111 to the remote receiver 113, anyknown wireless technology is anticipated for connecting the remotecontrol 111 to the processing element 100 including, but not limited to,radio frequencies (e.g., Bluetooth), sound (e.g., ultrasonic) and otherspectrums of light. Furthermore, it is anticipated that the wirelesstechnology be either one way from the remote 111 to the receiver 113 ortwo way.

The television internal synchronization signal 90 is generated by, forexample, the processing element 100. The processing element 100determines when a three-dimensional content is being displayed and whenleft-eye content or right-eye content is being displayed by receivingsuch indication on an input signal (e.g., HDMI, USB, etc) or extractingsuch information from the video display signal, for example, a specificset of pixels of each frame dedicated to indicate left-frame orright-frame. The processing element 100 communicates with an RFtransceiver 120 to initiate transmission of the synchronization packet57 at, for example, the start of the left-eye frame. In otherembodiments, the processing element 100 communicates with an RFtransceiver 120 to initiate transmission of the synchronization packet57 at the start of each frame and each synchronization packet 57includes an indication of which type of frame (left-eye or right-eye ortwo-dimensional) is being displayed.

In embodiments in which the television computes the latency l, the RFtransceiver 120 signals the processing element 100 when anacknowledgement of the synchronization packet 57 is received back fromthe eyewear 50A. The processing element 100 then determines theround-trip time from the start of transmission until the receipt of theacknowledgement and allocates a portion of the round-trip time togenerate a latency l value. The latency l value is then encoded into thenext synchronization packet 57 for use within the receiver 80/81 tocorrectly synchronize to the synchronization packet 57. In someembodiments, instead of transmitting the latency value to the receiver80/81 within the eyewear 50A, the processing element 100 uses thelatency value l to transmit the synchronization packet 57 earlier thanthe actual synchronization point so that, under normal conditions, thereception of the synchronization packet 57 by the receiver 80/81coincides with the synchronization point.

Equivalent elements can be substituted for the ones set forth above suchthat they perform in substantially the same manner in substantially thesame way for achieving substantially the same result.

It is believed that the system and method and many of its attendantadvantages will be understood by the foregoing description. It is alsobelieved that it will be apparent that various changes may be made inthe form, construction and arrangement of the components thereof withoutdeparting from the scope and spirit of the invention or withoutsacrificing all of its material advantages. The form herein beforedescribed being merely exemplary and explanatory embodiment thereof. Itis the intention of the following claims to encompass and include suchchanges.

1. A three-dimensional eyewear synchronization system comprising: atransmitter, the transmitter sends a synchronization packet indicating asynchronization timing between left-eye content and right-eye content;and three-dimensional eyewear having a receiver and a shutter system,the shutter system alternating image viewing to each eye of a wearer,the three-dimensional eyewear receives the synchronization packet,determines a transmission latency and uses a time of receipt of thesynchronization packet and the latency to generate an eyewear internalsynchronization timing that approximates the synchronization timing;whereas three-dimensional eyewear controls the shutter system responsiveto the eyewear internal synchronization timing.
 2. The three-dimensionaleyewear synchronization system of claim 1, wherein the transmitterdetermines the transmission latency and sends a value of the latency tothe three-dimensional eyewear within the synchronization packet and thethree-dimensional eyewear uses the time of receipt of thesynchronization packet and the latency value to generate the eyewearinternal synchronization timing that approximates the synchronizationtiming.
 3. The three-dimensional eyewear synchronization system of claim2, wherein the timing circuit locks onto the internal synchronizationtiming and the timing circuit continues operation of the shutter systemat times when the synchronization packets are not received.
 4. Thethree-dimensional eyewear synchronization system of claim 1, wherein atiming circuit within the three-dimensional eyewear determines thetransmission latency and uses the time of receipt of the synchronizationpacket and the latency to generate the eyewear internal synchronizationtiming that approximates the synchronization timing.
 5. Thethree-dimensional eyewear synchronization system of claim 4, wherein thetiming circuit locks onto the internal synchronization timing and thetiming circuit continues operation of the shutter system at times whenthe synchronization packets are not received.
 6. The three-dimensionaleyewear of claim 3, wherein the timing circuit includes a phased-lockedloop.
 7. The three-dimensional eyewear of claim 1, wherein thetransmitter is selected from the group consisting of a WiFi transmitter,a Bluetooth transmitter and an infrared transmitter.
 8. Thethree-dimensional eyewear of claim 1, wherein the transmitter isintegrated into a television.
 9. A method of synchronizingthree-dimensional eyewear to a display of content, the methodcomprising: at a synchronization point, sending a synchronization packetto the three-dimensional eyewear; determining a latency of the sending;generating an internal synchronization timing by combining a time ofreception of the synchronization packet with the latency; andcontrolling eye shutters of the three-dimensional eyewear insynchronization with the internal synchronization timing.
 10. The methodof claim 9, wherein the generating includes subtracting the latency fromthe time of reception.
 11. The method of claim 9, wherein the latency isderived from a size of the synchronization packet and a speed oftransmission of the synchronization packet.
 12. The method of claim 9,wherein the internal synchronization timing if adjustable by a manualskew adjustment.
 13. The method of claim 9, wherein the latency isdetermined by a sender of the synchronization packet and a digitalrepresentation of the latency is included in subsequent synchronizationpackets.
 14. The method of claim 13, wherein the sender is a television.15. A three-dimensional eyewear synchronization system comprising: atelevision, the television having a display, the display presentingleft-eye frames and right-eye frames; a means for transmitting asynchronization packet synchronized to which of the left-eye frame andthe right-eye frame is being displayed on the display, the means fortransmitting a synchronization packet associated with the television; ameans for receiving the synchronization packet associated withthree-dimensional eyewear; a means for determining a latency of themeans for transmitting the synchronization packet; and a means forsynchronizing shutters of the three-dimensional eyewear, the means forsynchronizing using a time of reception of the synchronization packetand the latency to approximate the timing of the display of the left-eyeframes and the right-eye frames.
 16. The three-dimensional eyewearsynchronization system of claim 15, further comprising a means forlocking, thereby continuing operation of the means for synchronizing theshutter in absence of the synchronization packet.
 17. Thethree-dimensional eyewear synchronization system of claim 16, whereinthe means for locking includes a phased-locked loop.
 18. Thethree-dimensional eyewear synchronization system of claim 15, whereinthe means for transmitting and the means for receiving uses a wirelesstransmission selected from the group comprising WiFi, Bluetooth andinfrared.
 19. The three-dimensional eyewear synchronization system ofclaim 15, wherein the means for determining the latency includes a meansfor determining a length of the synchronization packet and a means fordetermining a transmission rate of the means for transmitting.
 20. Thethree-dimensional eyewear synchronization system of claim 15, whereinthe means for determining the latency includes a means for determiningthe time of a transmission of the synchronization packet and a means fordetermining a time of a reception of an acknowledgement of receipt ofthe synchronization packet.
 21. The three-dimensional eyewearsynchronization system of claim 20, wherein the latency is digitallyencoded into a subsequent synchronization packet.
 22. Thethree-dimensional eyewear synchronization system of claim 15, furthercomprising a means for adjusting a skew of the means for synchronizingshutters.
 23. A three-dimensional eyewear synchronization systemcomprising: a television, the television having a display, the displaypresenting left-eye frames and right-eye frames; a synchronizationsignal representing a change between displaying of the left-eye frameand displaying of the right-eye frame on the display; a means fordetermining a latency of a transmission of a synchronization packet; ameans for transmitting a synchronization packet synchronized to thesynchronization signal retarded in time by the latency; a means forreceiving the synchronization packet associated with three-dimensionaleyewear; and a means for synchronizing shutters of the three-dimensionaleyewear to the reception of the synchronization packet, the means forsynchronizing approximating the timing of the display of the left-eyeframes and the right-eye frames.
 24. The three-dimensional eyewearsynchronization system of claim 23, further comprising a means forlocking onto the reception of the synchronization packet, therebycontinuing operation of the means for synchronizing the shutter inabsence of the synchronization packet.
 25. The three-dimensional eyewearsynchronization system of claim 24, wherein the means for lockingincludes a phased-locked loop.
 26. The three-dimensional eyewearsynchronization system of claim 23, wherein the means for transmittingand the means for receiving uses a wireless transmission selected fromthe group comprising WiFi and Bluetooth.
 27. The three-dimensionaleyewear synchronization system of claim 23, wherein the means fordetermining the latency includes a means for determining a length of thesynchronization packet and a means for determining a transmission rateof the means for transmitting.
 28. The three-dimensional eyewearsynchronization system of claim 23, wherein the means for determiningthe latency includes a means for determining the time of a transmissionof the synchronization packet and a means for determining a time of areception of an acknowledgement of receipt of the synchronizationpacket.
 29. The three-dimensional eyewear synchronization system ofclaim 23, further comprising a means for adjusting a skew of the meansfor synchronizing shutters.